the long road to pkg_add -u... and beyond

I will attempt to present most of the design choices that underlay the current workings of OpenBSD's pkg_*.

We currently have efficient updates, that can deal with rather bizarre update scenarios, with surprisingly little information stored within the packages themselves.

Even though the basic setup for those tools were finished two years ago, there have been a huge number of issues that have shown up after the tool was "finished".

This presentation will explain why, in retrospect, it was impossible to predict those issues beforehand, and why deploying what we had was the only practical way to run into the remaining issues and solve them.